MC and/or younger brother are athletes.
His parents are raising the younger brother's child, who is ages with his youngest sibling.
The children have him marked as a soft touch whenever he is making himself food and he's always having to make extra.
Sorry, that's it as far as my memory goes!
Any suggestions?
Nope! I almost added that it wasn't "Stupid Boy" in my description when I realised how it resonated. Thanks,
Or Douglas Fox's Life in Paradise series? Possibly Paying the Price 15 year old Andy gets his girlfriend pregnant, she doesn't want the kid but Andy does. Turns out there are twins and Andy's parents help him raise them.
Definitely one of the Life in Paradise series by Douglas Fox. Kyle Martin's older brother also has a child, which is in an earlier book than Paying the Price. I'd start with Lost & Found.
I accept that you were looking for the Douglas Fox story, but the description of that one reminded me of a story uploaded almost 19 years ago - https://storiesonline.net/s/49407/falling-for-my-step-sisters by bfrap.